I just wanted to add on another option to get a larger power supply into the OptiPlex 9010 Mini Tower case on the chance that someone looking for info on how to do this finds this discussion. As mentioned earlier, the latch mechanism prevents a larger size ATX power supply from easily sliding into place. To get around this, I uninstalled the motherboard, which gave me enough room to install a higher wattage power supply. My replacement power supply measured 3.4" x 5.9" x 6.1"/ 86mm x 150mm x 155mm, just a little bit too big to get past the latch - I tried multiple ways to angle it in place, none worked. I finally just removed the motherboard, installed the power supply, then reinstalled the motherboard. Uninstalling and reinstalling the motherboard only took about an extra 15 minutes.